as often as怎么用

Repeat this as often as necessary. =Repeat this action as many times as it is necessary。根据需要尽量多次重复这个动作。

句中的this指上句的… breathe into his／her mouth（向口里吹气）这个动作。often在这里可理解为：many times。

as…as意为：像……一样。引导表示比较的状语从句，在两个as之间插入形容词或副词。在第二个as后可接从句，但常保留从句

每当
后面接从句，一个完整的句子
As often as he's tried to go there, he's always failed.
每次他想去那里,总是去不成。本回答被提问者采纳

as often as 后面跟一件事情的发生